A huge explosion in NYC's East Harlem neighborhood happened Wednesday morning, prompting two five-story buildings to partially collapse. Authorities gathered at the scene at 1644 Park Ave. between 116th and 117th streets, and Metro-North train routes were suspended because debris from the explosion fell onto the tracks. Mayor Bill de Blasio made his way to the area, where he called the day's events "a tragedy of the worst kind." Reportedly, rumbles were felt 35 blocks away following the explosion, and as of Friday morning, eight deaths and 70 injuries had been reported. The explosion was caused by a gas leak, which left the five-story buildings in a three-story pile of rubble. By Thursday night, about 50 percent of the debris had been removed, with smoke still billowing as firefighters moved through the rubble.